This invention relates to a device for the dispensing or delivery of adhesive materials, more particularly, to a self-contained, portable device for the controlled, 1:1 ratio dispensing of a two-part epoxy adhesive from pre-filled cartridges and to the method of using the same.
Two-part adhesives are generally comprised of a resin component and a catalyst or hardener component. The two components are kept in separate containers and mixed together just before application. Often the resin and the catalyst are mixed in a 1:1 ratio. Two-part adhesives, such as two-part epoxy adhesives, are widely used in construction projects for various applications such as setting studs or anchors in preformed holes in concrete or masonary, or used as a joint filler in highway construction projects.
Generally, for use on construction projects, large doses of such adhesives are required. One application may consume the entire contents of many small, hand held cartridges. For larger applications, buckets of the separate adhesive components are poured into reservoirs on the dispenser and pumped out to the work surface. It is, therefore, an advantage to have a dispensing apparatus that can hold and dispense a large quantity of the two-part adhesive. For example, it is advantageous to have a dispensing machine that can hold and deliver up to 21/2 gallons or more of a two-part adhesive between refills so that work on a project can continue in an uninterrupted manner.
Commercial dispensing or pumping devices are known to the art. However, these prior art devices have significant drawbacks. For example, many prior art dispensers are designed as small, hand held devices which use small volume, pre-filled cartridges. As stated above, many such cartridges are required for one job. This is not cost effective, and, requires work stoppage during reloading of the dispensing devices.
Secondly, many of the large volume dispensing devices are not self-contained. They are designed for stationary use or require an external power source. For example, many of the larger devices are powered by compressed air and require a separate air compressor at the construction site. Providing a separate power source increases capital outlay and overhead costs. Moreover, air pressure pumps can be unreliable in response to changes in ambiant temperature. As the ambiant temperature of the adhesive drops, the adhesive materials get thicker and move slower at any given air pressure setting. This requires that the air pressure setting be constantly adjusted depending upon fluctuations in ambiant temperature. U.S. Pat. No. 5,020,693 to Ernst et al. and U.S. Pat. No. 4,067,479 to Moline disclose such devices requiring a separate air source.
Another disadvantage of the prior art large volume adhesive dispensing devices is that they utilize two reservoirs or hoppers to hold the resin and catalyst. Such devices are disclosed in U.S. Pat. No. 4,366,918 to Naka and U.S. Pat. No. 4,693,397 to Lang. Bulk containers or buckets of the resin and catalyst are dumped into each of the reservoirs. Due to the viscosity of the material, a substantial amount of adhesive material is retained in the bulk container and is wasted. As much as twenty percent (20%) of the bulk container may be wasted because it cannot be removed from the bucket. Additional adhesive is retained in the reservoirs and is discarded. This represents considerable waste of a product having a wholesale cost that can run in excess of $30 per gallon.
Attempts to remedy the aforestated deficiencies have included the use of pre-filled cartridges. As stated above, heretofore, the cartridges have necessarily been small, requiring the use of multiple cartridges for each application. On an economy of scale, this is a costly way to provide a epoxy for construction applications. Furthermore, there are other problems associated with small cartridges and the dispensing devices.
These dispensers usually are guns generally employing a plunger to force the material out of the cartridge. The more pressure applied to the cartridge, the greater the chance that the plunger will cause stretching of the cartridge which results in leakage of material between the cartridge and the plunger. Furthermore, the constant pressure applied to the contents of the cartridge by ratcheting or by a threaded screw-drive plunger forces the material out of the cartridge, resulting in unwanted dribbling or leaking out of the dispensing nozzle. Examples of such devices are disclosed in U.S. Pat. Nos. 4,758,536 to Spehar et al. and 4,986,443 to Saur et al.
Another type of adhesive dispenser is a pump employing a pair of double-action reciprocating pumps, one for the resin and one for the catalyst, which move product on both sides of the piston to a mixing head and out of a static mixer. Since the adhesive is drawn into one side of the pump and forced out of the other side, an obvious drawback to this design is the excessive wear and deterioration of the moving parts. Low-cost adhesive compounds have abrasives dispersed throughout. These abrasives can cause wear and damage to the reciprocating pump interior walls and piston as the material is drawn through the pump. As the pump wears it looses efficiency and fails to deliver appropriate quantities of each separate ingredient. For example, the quantities of product pumped through each pump may vary and thereby disrupt the required ratio of resin to catalyst.
It is, therefore, a principal object of the present invention to provide a self-contained, portable two-part adhesive dispenser capable of dispensing large volumes of adhesive material from large volume pre-filled cartridges.
It is another object of the present invention to provide a portable, two-part adhesive dispenser wherein pre-filled cartridges are inserted into a pair of cylindrical openings in a cartridge housing to prevent stretching of the cartridges and leakage under pressure during dispensing.
Another object of the invention is to provide a self-contained, portable two-part adhesive dispenser in which adhesive material is forced out of the pre-filled cartridges by a pair of plungers moving in unison with a hydraulic piston.
Yet another object of the invention is to provide a self-contained, portable two-part adhesive dispenser wherein a hydraulic dispensing piston is driven by pump powered by a a self-contained power source such as a small horsepower gasoline engine.
Still another object of the invention is to provide a self-contained, portable two-part adhesive dispenser in which expandable, flexible sealing plunger cups contact the adhesive material directly to force the adhesive material out of the cartridge and prevent escape of the adhesive behind the cups.
Another object of the invention is to provide a self-contained, portable two-part adhesive dispenser having no moving metal parts that come in contact with abrasives in the adhesive material.
Still another object of the invention is to provide a self-contained, portable two-part adhesive dispenser in which a hydraulic piston and dual plunger assembly is pivotable out of the way of a cartridge housing having cylindrical openings therein to provide access to the openings so that pre-filled cartridges can be loaded into and empty cartridges removed from the housing.
A further object is to provide a dispensing device which uses pre-filled cartridges, which cartridges have a central dispensing opening sealed with a severable cover in one end and a series of concentric grooves surrounding the opening, said grooves being aligned with seals on the dispensing device to prevent leakage when product is dispensed from the cartridges.
Still another object of the present invention is to provide a self-contained, portable two-part adhesive dispensing device in which the plungers can force all of the material out of pre-filled adhesive cartridges thereby avoiding waste.
Yet another object of the invention is to provide a self-contained, portable two-part adhesive dispenser having a minimum of moving parts, is simple and economical to manufacture and assemble, easy to transport and well suited for its intended purpose.
These and other objectives and advantages will become apparent hereinafter.